|a small query about Value numbering firstname.lastname@example.org (yugandhar balaji krishna atukuri) (2006-05-26)|
|Re: a small query about Value numbering Jeremy.Wright@microfocus.com (Jeremy Wright) (2006-05-26)|
|From:||"Jeremy Wright" <Jeremy.Wright@microfocus.com>|
|Date:||26 May 2006 12:48:37 -0400|
|Posted-Date:||26 May 2006 12:48:36 EDT|
According to "Advanced Compiler Design and Implementation", Steven S.
Muchnick, pg343, in the following example Global Common SubExpression
and Partial Redundancy Elimination both eliminate the third "2 * i" but
Value Numbering does not.
l := 2 * i
if i > 0 goto L1
j := 2 * i
L1: k := 2 * i
As others have commented before, Muchnick's book is excellent but there
is no hand holding. He expects you keep up with him.
> can anybody tell me a "case" which cannot be covered by VALUE
> NUMBERING and covered by Common subexpression elimination.
> personally i believe that Value numbering is Superior to common
> subexpression elimination and value numbering can optimize all the
> common subexpressions that can be optimized by common subexpression
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